The atypical antipsychotic risperidone is associated with weight gain and cardio-metabolic side effects. In light of growing evidence implicating the gut microbiome in the host’s energy regulation and in xenobiotic metabolism, it is hypothesized that risperidone-induced weight gain is mediated through alterations in the gut microbiome. The impact of chronic and short-term risperidone treatment on the gut microbiome of pediatric, psychiatric patients was examined in a cross-sectional and prospective design. Chronic treatment with risperidone was associated with a significant increase in body mass index (BMI) and a significant reduction in the ratio of Bacteroidetes to Firmicutes, as compared to naïve psychiatric controls. Predictive metagenomic analyses, indicate that gut microbiota dominating the risperidone-treated patients are enriched for pathways, such as short-chain fatty acid production, which have been implicated in weight gain. Alterations in the microbiome due to risperidone treatment were further demonstrated in wild-type female mice and shown to be a result of a reduction in host energy expenditure. Risperidone-treated mice exhibit significant weight gain and an altered gut microbiome relative to controls while maintaining normal food intake behavior and digestive efficiency, indicating that increased weight gain is due to reduced energy expenditure. Moreover, fecal transfer from risperidone-treated mice to a second cohort of naïve mice was performed via daily gastric gavage and aerobic and non-aerobic resting metabolic rates (RMR) were monitored using combined calorimetry. This transfer has no effect on aerobic RMR in recipients, but induces a significant suppression of non-aerobic RMR in mice receiving stool from risperidone-treated donors establishing a causal effect of the altered gut microbiome upon energy expenditure. Finally, daily transfer of phage, a subset of the gut microbiome, isolated from the gut of risperidone treated donors was also sufficient to cause excess weight gain in naïve recipients animals through suppression of energy expenditure. Together, these data highlight a major role for the gut microbiome for weight gain following chronic use of risperidone, and demonstrate that the mechanism depends upon suppression of energy expenditure.

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It is well understood that substantial health inequality exists for adults with an intellectual disability (AWID). In comparison to the general population AWID experience higher rates of morbidity and mortality associated with sedentary lifestyles, yet little is known about the role physical activity plays in preventing or mediating this outcome for this segment of society. Without appropriate instrumentation, it is not possible to address the inadequacies that currently exist in the area of physical activity and AWID. The primary aim of the series of studies in this thesis was to develop a psychometrically sound proxy-respondent measurement tool that could be used by researchers, epidemiologists and public health personnel to gather information on the physical activity behaviours of AWID. The International Physical Activity Questionnaire (IPAQ) is an internationally published tool with good psychometric properties when used as a self-report tool with adults without a disability (AWOID), but no evidence exists as to the validity or reliability of this tool when used by proxy respondents to report on the physical activity behaviour of AWID. Given little is known about the energy expenditure characteristics of AWID, nor the accuracy of tools developed for AWOID when applied to AWID, two secondary aims of this thesis were to measure the energy expended by AWID and AWOID during seven common activities of daily living (ADL) and to assess the accuracy of an objective physical activity measurement tool (Caltrac® accelerometer) for use with AWID. Evidence gathered through the studies in this thesis found that as the energy demand of ADL increased there was an increase in the difference between energy expended by AWID and AWOID. Results indicated that AWID achieved moderate-intensity physical activity when walking at a pace of 3.0 km/hr or more. The proxy-respondent telephone questionnaire (IPAQ-ID) described in this thesis allows for universal assessment of the physical activity behaviours of AWID. The IPAQ-ID was found to have measurement properties equivalent to measurement tools used among AWOID. The IPAQ-ID was found to be suitable for use as a surveillance tool by researchers to collect comparable data on health-enhancing physical activity behaviours of AWID.

Thesis (M.A. (Human Movement Science))--North-West University, Potchefstroom Campus, 2009.

Purpose. To investigate the validity of the Sense Wear Pro Armband (SWA) to measure energy expenditure (EE) in healthy participants using wheelchair ergometry as an exercise modality. Method. Minute by minute EE was measured simultaneously using the SWA and indirect calorimetry(IC) during three different wheeling speeds including self-selected speed (0.81 m/s), moderate speed (1.11 m/s), and fast speed (1.73 m/s). Results. Twenty healthy volunteers (age = 34.0 (5.8) years)participated. The intraclass correlation coefficients (ICCs) were 0.50 (p=0.010), 0.59 (p=0.003), and 0.68 (p=0.000) for the self-selected speed, moderate speed, and fast speed wheeling, respectively. The SWA overestimated EE 57.8%, 57.4 %, and 63.7% for self-selected speed, moderate speed, and fast speed, respectively. Conclusions. The SWA failed to provide an accurate estimate of EE as measured by indirect calorimetry for wheelchair ergometry exercise in healthy subjects. The SWA overestimated EE for all exercise intensities. / REHABILITATION SCIENCE-PHYSICAL THERAPY

This dissertation was designed to determine the effects of body mass index (BMI) and walking speed on activity monitor outputs. A secondary purpose was to compare the activity monitors’ performance in a free-living environment. In the first experiment, 71 participants wore three waist-mounted activity monitors (Actical, ActiGraph, and NL-2000) and an ankle-mounted device (StepWatch 3) while walking on a treadmill (40, 67 and 94 m/min). The tilt angle of each device was measured. The Actical recorded 26% higher activity counts (P < 0.01) in obese persons with a tilt <10 degrees, compared to normal weight persons. The ActiGraph was unaffected by BMI or tilt angle. In the second experiment, the steps recorded by the devices were compared to actual steps. Speed had the greatest influence on the accuracy these devices. At 40 m/min, the ActiGraph was the least accurate device for normal weight (38%), overweight (46%) and obese (48%) individuals. The Actical, NL-2000 and StepWatch averaged 65%, 73% and 99% of steps taken, respectively. Lastly, several generations of the ActiGraph (7164, GT1M, and GT3X), and other research grade activity monitors (Actical; ActivPAL; and Digi-Walker) were compared to a criterion measure of steps. Fifty-six participants performed treadmill walking (40, 54, 67, 80 and 94 m/min) and wore the devices for 24-hours under free-living conditions. BMI did not affect step count accuracy during treadmill walking. The StepWatch, PAL, and the AG7164 were the most accurate across all speeds; the other devices were only accurate at the faster speeds. In the free-living environment, all devices recorded about 75% of StepWatch-determined steps, except the AG7164 (99%). Based on these findings, we conclude that BMI does not affect the output of these activity monitors. However, waist-borne activity monitors are highly susceptible to under-counting steps at walking speeds below 67 m/min, or stepping rates below 100 steps/min. An activity monitor worn on the ankle is less susceptible to these speed effects and provides the greatest accuracy for step counting.

In this dissertation we analyze the role of parties’ electoral competition in aggregating voters’ preferences over policy and its impact on tax design. The representation of voters’ interests is central for the analysis of public finance since the issue of aggregation is closely linked to the tradeoff between efficiency and redistribution, and the size and composition of public spending. Parties’ aggregation of preferences is related to the mechanism in which policy makers (parties) weigh the relative merits of competing goals of the tax system (in our analysis, redistribution versus efficiency), and reveals the welfare calculus throughout parties identify groups of individuals who might be beneficiated (hurt) by policy changes. In the first essay we analyze the influence of voters in modifying tax policy through tax initiatives. In this essay we argue that the process of aggregation of preferences between the competition for votes in a representative democracy and the majority rule are different. This, in turn, might lead to the approval of a tax rate limit (TRL) initiative. We argue that the rationale for a TRL proposal is to substitute feasible tax structures rather than to constrain the government’s power to collect taxes. In addition, we provide a model that predicts the tax structure that would arise as a result of a TRL The second essay addresses the role of voters’ partisan attitudes in the determination of fiscal policies. We argue that partisan attitudes and its distribution across the electorate influence the proportion of the expected votes that different coalitions deliver in the election. We identify conditions in which voters’ partisan attitudes affect the provision of a public good and the redistributive properties of the tax structure. The third essay extends our previous analysis of the impact of voters’ partisan attitudes on tax design by incorporating parties that are policy motivated. In this setting, the relative merits of efficiency versus redistribution in designing the tax system are determined by the process of aggregation of voters’ preferences and parties’ preferences over policy. The conflict between parties and the electorate’s preferences over tax policy depends on voters’ partisan attitudes. In particular, voters’ party affiliation soft parties’ electoral constraints, allowing parties to advance the interests of their constituents. The model predicts that redistribution (efficiency) will play a more prominent role for a party that represents a coalition of low (high) income individuals with a high (low) taste for public goods.

Social support has been recognized to impact positive health behaviours, including exercise participation. In the exercise domain, one conceptual framework that has been employed to examine social support is Weisss (1974) Model of Social Provisions. The main purpose of the present study was to utilize Weisss (1974) model to examine how the social provisions relate to university students energy expenditure while exercising with others. Specifically, this study was concerned with participants perceptions about the availability of social provisions, their preferences for the provisions in the exercise setting, and the congruence between social provision perceptions and preferences as they related to energy expenditure. Participants who had performed exercise with others in the past 4 weeks (N=201) completed the Modifiable Activity Questionnaire (MAQ; Kriska et al., 1990) to assess energy expenditure, as well as modified versions of the Social Provisions Scale (Cutrona & Russell, 1987) to assess social provision perceptions and preferences. Results from exploratory factor analyses revealed separate five-factor models for both the perceived provisions (i.e., attachment, reliable alliance, social integration, opportunity for nurturance, and reassurance of worth) and the preferred provisions (i.e., guidance, social integration, reliable alliance, reassurance of worth, and opportunity for nurturance). Discriminant function analyses were used to assess the unique contribution of these perceived and preferred provisions to participants energy expenditure. The results from the analyses indicated that none of the perceived provisions and none of the preferred provisions predicted high versus low expenditure, nor did the congruence relationship between the perceived and preferred variants of each provision predict high versus low energy expenditure. Potential explanations for the non-significant findings were highlighted with respect to study methodology. Directions for future research were also discussed.

This dissertation comprises two essays that attempt to determine, empirically, the fiscal response of governments’ to international assistance. The first essay examines whether an increasingly popular recommendation in international aid policy to switch from tied foreign assistance to untied foreign assistance affects investment in critical development expenditure sectors by developing countries. In the past, most international aid has been in the form of tied assistance as donors believed that tying aid will improve its effectiveness. It has been argued, that if tied aid is well designed and effectively managed then its overall effectiveness can be improved. On the contrary, it is also believed that tied aid acts as an impediment to donor cooperation and the building of partnership with developing countries. In addition, it is also argued that it removes the ‘feeling’ of ownership and responsibility of projects from partner countries in aid supported development. Two other more popular arguments used to challenge the effectiveness of foreign aid is that it is compromised when tied to the goods and services of the donor countries because almost 30 percent of its value is eliminated and also because it does not allow recipient countries to act on their priorities for public spending. These problems bring into question whether tied aid is truly the most effective way to help poor countries. A recommendation by the international community is that a switch to untied aid would be necessary. With untied aid, the recipient country is not obligated to buy the goods of the donor country neither is it compelled to pursue the public expenditure priorities of donors. Instead with untied aid they will have greater flexibility over spending decisions and can more easily pursue the priorities of their countries as they see fit. Hence, one could expect that a one dollar increase in untied aid will increase spending in the critical priority sectors by more than a one dollar increase in tied assistance. The question therefore is whether national domestic priorities coincide or not with what the international community has traditionally deemed should be priority. Empirically, we test this prediction using country-by-country data for 57 countries for the period 1973 to 2006. The results suggest that on average untied aid has a greater impact on pro-poor spending than do tied aid. In addition, the results also suggest that fungibility is still an issue even after accounting for the effects of untied aid. However, one could argue that fungibility may not be as bad as it appears since the switch to untied aid improves spending in the sectors that are essential for growth and development. The second essay explores the hypothesis that the expectations of debt forgiveness can discourage developing countries from attaining fiscal independence through an improvement of their tax effort. On the one hand, the international financial community typically advises poor countries to improve revenue mobilization but, on the other hand, the same international community routinely continues to bail-out poor countries that fail to meet their loan repayment obligations. The act of bailing-out these countries creates an expectation on the part of developing country governments that they will receive debt forgiveness time and again in the future. Therefore, the expectation of future bail outs creates a moral hazard that leads to endemic lower tax efforts. The key prediction of our simple theoretical model is that in the presence of debt forgiveness, tax ratios will decline and this decline will be stronger the higher the frequency and intensity of the bailouts. Empirically, we test this prediction using country-level data for 66 countries for the period 1989 to 2006. The results strongly suggest that debt forgiveness plays a significant role in the low tax effort observed in developing countries. Our empirical model allows for the endogeneity of tax effort and debt forgiveness. Interestingly we find that more debt forgiveness is actually provided to countries with lower tax effort. The results are robust to various specifications.

Food and nutrition policy analysis, especially for a developing country, requires information on food price and expenditure elasticities. Often, such information is not readily available for different income groups. For Lesotho, this information currently does not exist. This study analyses the food consumption and nutrition of households in Lesotho by estimating a set of food demand parameters. The Lesotho government, in the process of developing the agriculture sector, aims to increase the domestic production of maize through the Food Self Sufficiency Programme (FSSP) by providing incentives to producers. The FSSP has the potential to affect prices at the consumer level for maize and maize meal. Higher maize meal prices could have adverse nutritional impacts especially for low income households. The objective of this study was to analyze the effects of price and income changes on the nutritional well being of consumers with a focus on low income households. A related objective was to provide an estimate of the parameters for food demand. The Almost Ideal Demand System was used to estimate demand parameters for seven food groups: maize, other cereals, meat, milk, eggs, fats and oils, and fruits and vegetables. Data for analysis was obtained from the Household Budget Survey (HBS) that was carried out in 1986/87 by the Bureau of statistics over a twelve month period. Households were divided into low, middle and high income groups. The share equations were first estimated by imposing the homogeneity and symmetry restrictions. The null hypothesis of symmetry given homogeneity is not rejected in any of the income groups. The results of the estimation indicate that total food expenditure elasticity declines as income increases. The sign and magnitude of the elasticities indicates that all food groups are relative necessities. Expenditure elasticity of maize declines from 0.91 for the low income group to 0.47 for the high income households. The estimated demand and expenditure elasticities were used to calculate calorie and protein price and expenditure elasticities for the low income households. (Abstract shortened by UMI.)